SlideVOLC

Large-scale deformation and flank instabilities of volcanoes represent a significant hazard because they can lead to major edifice destabilizations and large landslides. In an island environment, flank collapse can also trigger tsunami with catastrophic impacts on the coastline population of proximal and distal locations. Basaltic volcanoes, like Etna (Italy), Hawaiian volcanoes (USA) and Piton de la Fournaise (La Réunion Island, France), are amongst the largest volcanic edifices on Earth. On these huge active volcanoes, the continuous action of magmatic pressure leads to large deformation areas that ultimately control the volcano structure and topography with more or less mobile flanks, which respond to long-lasting stress field conditions (gravitational stress, magmatic processes and/or regional tectonics...). On La Réunion, a major destabilization of the Piton de la Fournaise flank occurring today would trigger tsunami with catastrophic impacts on the coastline population of the island and around the Indian Ocean. Indeed, 80% of the 840,000 inhabitants of La Réunion and most of the economic activities are located on the coastal fringe. It is thus of major interest for the scientific community to study and understand the large-scale deformation and flank instabilities of volcanoes and for society to educate the public on this hazard that is currently disregarded on effusive basaltic volcanoes, especially on La Réunion where the volcano is known as a popular hike, especially during eruptive stages. Our capability of predicting such catastrophic events relies on both our understanding of the complex link between the stress field, the volcanic and hydrothermal processes, and our ability to interpret the monitored signals as precursors. This project, focussed on Piton de la Fournaise volcano, aims to integrate new geophysical and geochemical observations into a coherent, global and realistic model. We propose i) to bring new inputs to the models with the imaging, via multi-disciplinary innovative methods, of the extent of the volcano deformation, the main fracture networks, the hydrothermal system, and by constraining the true edifice rheology, and ii) to use this new information to model the deformation distribution over the volcano and the flank destabilization dynamics. The final purpose is the production of a realistic “3D numerical volcano”, i.e. an integrated model of volcano edifice deformation using realistic rheology and hydro-mechanical coupling (with physical scenarios of the 3D thermal and deformation regimes of the Piton de la Fournaise’s edifice), aiding an understanding of the volcano flanks stability and dynamics, and able to predict the time and scale evolution of edifice deformation during and between eruptive events. This project is particularly innovative as it combines the integration of new data from multidisciplinary studies into improved numerical modelling and produces a realistic numerical volcano. The knowledge accumulated on Piton de la Fournaise will be exported to other volcanoes worldwide, notably Etna and Kilauea, which share common features with Piton de la Fournaise, most notably flank instabilities and huge landslides during their past activity. This project, which includes both observations and modelling, involves a research team that has all the skills and abilities required to conduct and carry out such a study. This frame ensures ideal conditions that can extend our research methods to similar volcanoes in Europe and worldwide.